(Name recused here) used 10 round magazines for his AR-15: (name recused here) ..... And the gun apparently may have jammed. (Name recused here)'s semiautomatic rifle may have jammed during the massacre at a high school in Parkland earlier this month, according to Miami Herald news partner.
I think the point to be taken here is that "Jam-O-Matic Boy" (name recused here) suffered the same awkward dysfunction which often plagues competitive shooters; if you don't test your magazines under stress (competion), you may inevitably discover that your magazines will not feel reliably.
In competition, this is A Bad Thing.
When your goal is to suffer your fellow citizens ...
we love it when incompetent people can't get it together!